Motion reproducing unit



Dec. 24, 1935. E. J. POITRAS rrr AL 2,025,122

MOTION REPRODUCING UNIT Filed June 6, 1935 fibg' .1

2 km 24 l 1 16 INVENTORS Edwaad-l oiia'as ga/mes D. Tea/r THEIR ATTORNEYPatented Dec. 24, 1935 MOTION REPRODUCING UNIT Edward J. Poitras,Jackson Heights, and James D.

Tear, Great Neck, N. strument Company, N. Y., a corporation Y.,assignors to Ford In- Inc., Long Island City, 1 New York ApplicationJune 6, 1935, Serial No. 25,209

13 Claims.

The invention herein disclosed relates to a motion reproducing unit inwhich the movement of one object is reproduced by another, the latterobject being actuated by a prime mover.

There has been, heretofore, devised a unit of this type in which thereis no hunting or appreciable overrunning of the following or drivenobject during rapid changes or reversals in the velocity of the elementor motion receiving member which is followed by the driven member. Inthis unit, the prime mover actuating the driven two cooperating controlis actuated in accordance with the driven member and the other of whichis actuated in .accordance with the motion receiving member. Relativemovement of these cooperating control elements affects the operation ofthe prime mover. Upon movement of the motion receiving member, there iseffected relative movement between the control elements and theoperation of the motor is efiected. Upon operation, the relation of thecooperating control elements is affected in accordance with the velocityof the prime mover so that the prime mover assumes a velocityproportional to the displacement of the control element actuated by themotion receiving member. A mechanism is also provided whereby the actualmovement of the motor is proportional to the movement of the motionreceiving member so that the driven object actuated by the motor has amovement corresponding to the movement of the motion receiving member.

While this unit eleminates the hunting and overrunning of the drivenobject, there is a lag of the driven object behind the motion receivingobject fora constant velocity of the motion receiving member.Consequently, where synchronous operation and positional agreementbetween the motion receiving and drivenmembers are desirable, this unitis not-suitable, and it is an object of this invention to provide a unitof this type in which the driven object is actuated in synchronousrelation, or positional agreement with the motion receiving member.

In accordance with the invention, the relation of the control elementswhich aifect the operation of the prime mover is modified in accordancewith changes in the velocity of the prime mover, that is, in accordancewith the second derivative of position of the prime mover. With thisunit, the motion receiving and driven members are in positionalagreement during operation at a constant velocity and the driven memberlags behind the motion receiving member only when there are rapidchanges in velocity.

Such a unit is illustrated in drawing in which:

Fig. 1 is a side elevation of the unit with certain parts removed;

Fig. 2 is a sectional end elevation taken on the line 22 of Fig. 1;

Fig. 3 is a view similar to Fig. 2 illustrating the control elementsunder conditions of acceleration; and

Fig. 4 is a figure similar to Fig. 2 illustrating the control elementsduring a condition of constant velocity of the motion receiving member.

The several parts of the unit illustrated in the drawing are mountedupon a base i The motion receiving member is represented as .a gear 2forming an input to one side of a difierential 3. The other side of thedifferential is connected through back gearing to an electric motor 4.The back gearing consists of an idler 5a meshing with a gear 6 of thedifferential and a gear 5 secured on a shaft 1. The shaft 1 is journaledin bearing brackets 8 and 9, the bearing bracket 8 beingsecured to thebase i and the bearing bracket 9 being formed on the motor. A gear l0secured on the end of the shaft i meshes with a pinion ll secured on theshaft of the motor which extends through both ends of the motor casing.The gear I0 drives the driven member and for the purposes of thedisclosure may be taken as the driven member.

The difierential 3 is 'mounted between bearing brackets 12 and I3secured to the base i. A hub 3a of one side of the differential on whichthe 5 gear 2 is formed is journaled in the bearing bracket 82 and thecentral shaft M of the differential to which the spider 3b is secured isjournaled in the bearing bracket l3. The shaft I 4 of the diiferentialisin axial alignment with 40 the shaft of the motor 4.

On the end of the shaft M, facing the motor, there is mounted ayieldable cam drive i5. Through this yieldable coupling there is drivena contact arm I6 which carries two spaced electrical contacts lfia. andl6b. The gear ratio between the motor and the diiferential 3 is suchthat movement of the shaft I 4, and the contact arm l6 secured thereto,represents the diiference in movement between the driven object and themotion receiving member represented by the gear 2.

The contacts [6a and Ifib cooperate with a double contact I! mountedupon an arm l8, the double contact I! extending between the two contheaccompanying 2 tacts Ilia and I6b. The arm I8 is rotatably mounted upona shaft I9 and it is maintained in a vertical position by centeringsprings 28 and 2I which extend between the arm I8 and standards 22 and23, respectively, secured to the base I. The arm I8 includes a crank armI8a which extends at right angles thereto. To this crank arm I8a thereis pivotally secured one end of a piston rod 24, the other end of whichis secured to a piston 25 of a dash pot 28.

The cylinder of the dash pot is carried by a crank arm 2Ia extendingfrom an arm 28 secured to the shaft IQ for rotation therewith. The arm28 is also normally maintained in a vertical position by centeringsprings 29 and 30 which extend between the arm 28 and the standards 22and 23 respectively.

The shaft I9 is journ led in and extends through a bearing bracket 3|which is secured to the base I. The end of the shaft I9 extends into thecase of aviscous drag 32, and on the end of the shaft, within the caseof the viscous drag, there is mounted on the shaft I9 a disk 33. Thecase 32 of the viscous drag is mounted upon the motor shaftfor rotationtherewith; the case is sealed and contains a viscous fluid such as oil.With this arrangement, there is exerted on the arm 28 a torque that isproportional to. the velocity of the motor 8 and the arm 28 is displacedfrom its central or neutral position an amount that is proportional tothe velocity of the motor.

The motor is split phase motor and it is connected to the contacts I6and I1 so that when the double contact II engages the fixed contact I6athe motor operates in one direction and when the double contact I'Iengages the contact I8b the motor operates in the opposite direction.

In the operation of the unit, the gear 2 is rotated, this gear beingconnected to any element the motion of which it is desired to reproducein the driven element. When the system is at rest, the electricalcontacts are in the position illustrated in Figure 2. Upon movement ofthe motion receiving member, when the motor is at rest, the contact armI6 is moved relative to the contact arm I8. Assuming that the motionreceiving member 2 is turned in a clockwise direction when the system isviewed as illustrated in Figure 2, the contact arm It will move in aclockwise direction and the contacts I61) and I1 will engage. When thesecontacts engage, the motor begins operating. Through the viscous drag32, the arm 28 is displaced from its neutral position as illustrated inFigure 3 an amount proportional to the velocity of the motor. Throughthe dash pot 26, the contact arm I8 is also displaced, being advanced inaccordance with the arm 28. If the arms I8 and 28 were rigidly securedtogether, the arm I8 would be displaced or advanced an amountproportional to the velocity of the motor and the contact I'I would rideupon the contact IBb in a position angularly displaced from its neutralposition an amount proportional to the velocity of the motor. Theintermittent contact under the conditions assumed is just enough to keepthe motor at a. velocity proportionalto the movement of the motionreceiving member. The back gearing of course acts to ofiset the movementof the motion receiving member so that, under the conditions assumed,the contact arm I6 would be displaced from its neutral position only anamount sufflcient to maintain the lag necessary to acquire the requisitevelocity. However, the arm I8 tends to return to its neutral position,the dash pot permitting-it to return gradually so that the arms I8 and28 assume a relative position, for a constant velocity of the motionreceiving member as indicated in Figure 4. In moving to its neutralposition, the arm I8 erases the lag between the driven object 5 and themotion receiving member so that these -members are in positionalagreement when the motion receiving member is operating at a constantvelocity. Upon rapid changes in velocity, the arm I8 follows the arm 28,but for gradual changes in velocity, the arm I8 is advanced inaccordance with the changes in velocity 50- that the driven object andthe motion receiving object are maintained in positional agreement.Operation of the unit in the opposite direction is the same as describedabove.

From the above it will be seen that there is produced in this unit anarrangement whereby the relation of the control elements or contacts ismodified in accordance with changes in the velocity of the prime mover.The result is that the movable and driven objects are maintained inpositional agreement for all conditions except those of rapidacceleration and deceleration when the driven object may lag slightlybehind the motion receiving member. However, upon the cessation of theserapid changes in velocity, the driven object is quickly brought intopositional agreement with the motion receiving member.

The yieldable drive coupling is provided between the shaft I4 and thearm I8 for the purpose of relieving any strain upon the controlelements. It may be omitted in so far as the fundamental principle ofoperation of the unit is concerned.

It is obvious that various changes may be made by those skilled in theart in the details of the embodiment disclosed in the drawing and de-'scribed in detail above within the principle and scope of the inventionas expressed in the ap- 40' pended claims.

, We claim:

1. In a unit of the type described, the combination comprising a movablymounted motion receiving member, a movably mounted driven member, aprime mover for driving the driven member, and means for controlling theprime mover including two relatively movable, coo-perating controlelements and means actuated by the relative movement thereof foraffecting the operation of the prime mover, means for effecting relativemovement of the control elements upon relative movement between themotion receiving and driven members, and means mechanically connectingthe prime mover and one of the 5 control elements for modifying therelation of said control elements in accordance with the acceleration ofthe prime mover.

2. In a unit of the type described, the combination comprising a movablymounted motion receiving member, a movably mounted driven member, aprime mover for driving the driven member, and means for controlling theprime mover including two relatively movable, cooperating controlelements and means actuated by the relative movement thereof forafiecting theoperation of the prime mover, means for efiectingrelativemovement of the control elements upon relative movement betweenthe motion receiving and driven members, and means mechanicallyconnecting the prime mover and one of the control elements for advancingone of said control elements in accordance with the acceleration of theprime mover.

3. In a unit of the type described, the combina- 7 5 1 for affecting therelation of the tion comprising a movably mounted motion receivingmember, a movably mounted driven member, a prime mover for driving thedriven member, and means for controlling the prime mover including tworelatively movable, cooperating control elements and means actuated bythe relative movement thereof for affecting the operation of the primemover, means for effecting relative movement of the control elementsupon relative movement between the motion receiving and-driven members,and means mechanically connecting the prime mover and one of the controlelements for modifying the relation of said control elements includingmeans for creating a torque on one of said control elements proportionalto the acceleration of the prime mover.

4. In a unit of the type described, the combination comprising a movablymounted motion receiving member, a movably mounted driven member, aprime mover for driving the driven member, and means for controlling theprime mover including two relatively movable, cooperating controlelements and means actuated by the relative movement thereof foraffecting the operation of the prime mover, means for effecting relativemovement of the control elements upon rel ative movement between themotion receiving and driven members, and means for modifying therelation of said control elements including means for advancing one ofsaid control elements comprising means displaceable in accordance withthe velocity of the prime mover, and means displaceable thereby inaccordance with the acceleration of the prime mover.

5. In a unit of the type described, the combination comprising a movablymounted motion receiving member, a movably mounted driven member, aprime mover for driving the driven member and control means for theprime mover including two relatively movable cooperating controlelements, means for effecting relative movement of the control elementsupon relative movement between the movable and driven members and meansfor affecting the operation of the prime mover including means operativein accordance with the velocity of the prime mover control elements andintroducing an error in the relation of the movable and driven members,and means for erasing the error.

6. In a unit of the type described, the c0mbi nation comprising amovably mounted motion receiving member, a movably mounted drivenmember, a prime mover for driving the driven member and control meansfor the prime mover including two relatively movable cooperating controlelements, means for efiecting relative movement of the control elementsupon relative movement between the movable and driven members and meansfor aiTecting the operation of the prime mover including means operativein accordance with the velocity of the prime mover for affecting therelation of the control elements and introducing an error in therelation of the movable and driven members, and means operative inaccordance with the displacement be-= tween the movable and drivenmembers for erasing the error.

7. In a unit of the type described, the combination comprising a movablymounted motion receiving member, a movably mounted driven member, aprime mover for driving the driven member and control means for theprime mover including two relatively movable cooperating controlelements, means for effecting movement of one of the control elementsupon relative movement between the motion receiving and driven membersto affect the operation of the prime mover, and means for affecting theother of the control elements including means operative in accordancewith the velocity of the prime mover and additional means operative inaccordance with the velocity of said last mentioned means.

8. In a unit of the type described, the combination comprising a movablymounted motion receiving member, a movably mounted driven member, aprime mover for driving the driven member and control means for theprime mover including two relatively movable cooperating controlelements, means for effecting relative movement of the control elementsupon relative movement between the motion receiving and driven members,and means for affecting one of said control elements in accordance withchanges in the velocity of the prime mover including means for eifectingpositional agreement between the movable and driven objects duringoperation of the prime mover at constant velocity.

9. In a unit of the type described, the combination comprising a movablymounted motion receiving member, a movably mounted driven member, aprime mover for driving the driven member and control means for theprime mover including two relatively movable cooperating controlelements, means for efiecting relative movement of the control elementsupon relative movement between the motion receiving and driven members,and means for affecting one of said control elements in accordance withchanges in the velocity of the prime mover including means for effectingpositional agreement between the movable and driven objects duringoperation at constant velocity, said latter means comprising a flexibleconnection with the control element and means for positioning thecontrol element.

10. In a unit of the type described, the combination comprising amovably mounted motion receiving member, a movably mounted driven 1 trolelement for movement of the control element upon movement of saiddisplaceable means, and means for returning the control element duringoperation of the prime mover at constant velocity.

11. In a unit of the type described, the combination comprising amovably mounted motion receiving member, a movably mounted drivenmember, a prime mover for driving the driven member and control meansfor the prime mover including two relatively movable cooperating controlelements,- means for effecting relative movement of the control elementsupon relative movement between the motion receiving and driven members,and means for afiecting one of said control elements in ac:ordance withchanges in the velocity of the prime mover including a movably mountedelement. means for displacing the element in accordance with thevelocity of the prime mover, a dash-pot interconnecting the movablymounted element and the control element, and centering springs acting tocenter the control element.

12. In a unit of the type described, the combination comprising amovably mounted motion receiving member and control means for the primemover including two relatively movable cooperating control elements,means for effecting relative movement of the control elements uponrelative movement between the motion receiving and driven members, andmeans introducing an error in the relation of the movable and drivenmembers proportional to the velocity of the prime mover including meansfor erasing the error.

member, a movably mounted driven member, a prime mover for driving thedriven- 13. In a unit of the type described, the combination comprisinga movably mounted motion receiving member, a movably mounted drivenmember, a prime mover for driving the driven member and control meansfor the prime mover including two relatively movable cooperating controlelements, means for effecting relative movement of the control elementsupon relative movement between the motion receiving and driven membersto affect the operation of the prime mover, and means for introducing anerror in the relation of the movable and driven members in accordancewith the velocity of the prime mover, said last mentioned meansincluding means operative in proportion to the error introduced forerasing the error.

EDWARD J. POITRAS.. JAMES D. TEAR.

DISCLAIMER Neck, 1935. ment Company, Inc.

N. Y. MOTION REPRODUCING UNIT.

Disclaimer filed September 18, 1937, by'the assignee,

N. Y., and James D. Tear, Great Patent dated December 24,

Ford Instru- Hereby enters this disclaimer to claims 1, 2, and 3 ofsaidPatent No. 2,025,122.

[Ojicz'alGazette October 12 1937.]

